Georg Fischer Aktiengesellschaft

Franz Hofmann

Rolf Rietzscher

Franz Satmer

Jurgen Otto

Wolfgang Kaettlitz

Gerd Trinki

Franz Szatmari

Hans G Trapp

A ceramic filter for filtering molten iron is disclosed. The ceramic filter is made from a high-melting ceramic material having an open-celled foam structure, a variable bulk density in different portions of the filter, and at least one afflux surface. In order to filter molten iron efficiently, the ratio of filter surface to filter volume should be in the range of about 0.0003 to 9 m.sup.2 /cm.sup.3, the specific filter resistance should be in the range of about 0.1 to 0.9 bar-cm at a flow rate of 5 m.sup.3 /hour, and the pressure loss .DELTA.p across the filter should depend on the specific resistance .rho., the filter length, and the surface area of the afflux plane F in accordance with the relationship: ##EQU1## A method for filtering molten iron using this ceramic filter is also disclosed. In this method, the ceramic filter is located near the point in the casting system where the molten iron has its greatest kinetic energy. The molten iron is first caused to flow tangentially by the afflux plane of the ceramic filter and then is deflected to create turbulence directly before the afflux plane of the filter.

Ceramic filter and method for using same

Regeneration of clay-bonded used foundry sand for reuse instead of new sand. A dry mass of used sand is rubbed for such a length of time, is accelerated suddenly and delayed, and is freed continuously of fine components, until the fine matter, active bonding clay and oolitization degree fall below certain threshold values such that the regenerated product substantially gains the characteristics of new sand. An apparatus for regeneration treatment contains a horizontal revolving sand drum (10), an impact rotor (30) disposed inside said drum in the area of the fall stream (46) of the used sand and a pneumatic dust removal device (36) disposed in the inside of the drum. A chemical secondary treatment of the regenerated product can be carried out advantageously in the same installation in order to bind remaining fine matter to the surface of the grains of sand and simultaneously to seal the pores of the grains.

Apparatus for regenerating used foundry sand

There is disclosed a process for applying a refractory filler and a hydrate of Al(H.sub.2 PO.sub.4).sub.3 or polyphosphates as a binder to a single or multi-layered carrier material to form a single or multi-layered, thin-walled structure subsequently hardened on the carrier material. The hardening is preferably conducted at a temperature below 400.degree. C. There is thus obtained a phosphate-bonded, thin-walled shaped article which is refractory at temperatures above 1300.degree. C.

Process for the production of molded phosphate bonded refractory articles

Rotary mixing apparatus particularly suitable for treatment of foundry sand having a drum mounted for rotation about an axis which is horizontal, or at least approximately horizontal, operates to treat bulk material such as foundry sand which is placed within the rotating drum. Stationary deflection apparatus is arranged within the drum in the upper range thereof and a rotating impact rotor is mounted within the drum so that as the drum rotates and the material contained therein is propelled into the upper region of the drum it is deflected by the deflection apparatus and formed into a downwardly falling jet which is directed at the rotating impact rotor.

Growing community of inventors

Neuhausen, Switzerland

Franz Hofmann